Police seized dagga and other drugs from pupils during raids at two Soweto high schools on Tuesday.
Warrant Officer Kay Makhubela said a pupil was found with 35 packets of nyaope [a cocktail of addictive drugs] which he had apparently been selling for R30 each.
Police also confiscated money from the 14-year-old Grade Nine pupil.
At the second school, police took dagga from 11 pupils.
"One of the girls had mixed her dagga with Zam-Buk, making it more potent," he said.
Other pupils were found with cigarettes, which they were selling to fellow pupils.
Makhubela said the pupils were expected to arrive at the police station with their parents on Wednesday. Some would be placed in rehabilitation centres.